text:
Principle of aerodynamic lift: are misconceptions also taught in flight schools?
Describing lift as the result of "equal transit time" on both sides of an airfoil is a fallacious theory widely found in technical books and articles for general public (see below for details about this explanation).
But such explanation is also found in aviation books, in spite being identified by NASA as an incorrect theory (NASA explains that if lift is computed from fluid laws, based on airspeed on both sides of the airfoil, the result will not be in line with what is observed in real life).
Question
Is this very popular theory also taught this way in flight schools? (please note the question is about pilot teaching, not about what is lift.)

Annex: Popular explanation of lift from equal transit time:
Supporters of this theory explain aerodynamic lift results from the differential of pressure between lower and upper sides of a wing created by Bernoulli principle. They say:

Air has to move a longer distance on the upper side because of the curve of the profile (not correct for all wing profiles).
Both sides must be traveled in an equal amount of time so that air molecules that were nearby ahead of the wing, will meet again behind it (may be right or wrong.)

By Bernoulli's principle accelerated airflow has lower pressure. Pressure is then lower on top of the wing, and higher on bottom. Hence the wing receives a force which has a vertical component upward. This component balances the weight of the aircraft, and allows to stay aloft.

this is well discussed over on the physics.SE: http://physics.stackexchange.com/questions/290/what-really-allows-airplanes-to-fly

Very good. I'm adding this reference to the question section. Note the question is about what is taught at flying school.

The See How It Flies explains physics relevant for flying aircraft, including lift and it is targeted specifically at aviators.

The "Bernoulli vs Newton" is the biggest nonsense. The actual answer is "Bernoulli and Newton" and it's actually Newton's first law (inertia of the stream is needed get stall in the picture).

@JanHudec: "Bernoulli vs Newton" retrieves more results from Google, this was the point. The 3 laws of motion seem to apply in lift generation. Air downwash is balanced by lift, according to 3rd law (see this slide for clarity).

@mins: It might retrieve more results, question is whether they are more correct results. Of course the downwash is balanced by lift and vice versa by 3rd law, but it does not explain why the wing produces downwash in the first place. For that you need to consider inertia of the air flowing along the oblique surface and leaving the trailing edge (the first law) and Bernoulli's equation to calculate the pressure field. And by then the math becomes pretty complicated and has numerical solution only.

Newton's law explains why pushing the air down pushes the aircraft up. It doesn't explain why the air gets pushed down in the first place.

Conversely, Bernoulli's law explains why the air goes down, but not why the aircraft goes up.

@immibis : The Bernoulli explanation, at least as it is usually presented  (changes in airflow speed create changes in pressure) doesn't explain why the airflow speed changes. 'Equal transit time' is an incorrect attempt to explain that. Bernoulli's law does not even explain the relationship between pressure and speed; it asserts it as a fact. Any causal explanation for that fact starts from Newtonian mechanics.

@JanHudec : I have no problem with Bernoulli's law being included in an explanation, but the fact is that Newton explains Bernoulli, and not the other way round. As I implied in my reply to immibis, if you start from Bernoulli, you reach the point where you need to explain why the airflow velocity changes, and that has been the point of introduction of many falsehoods, including the 'equal transit time' fallacy.

@sdenham: I agree.

Note that as stated, lift from downwash is perfectly valid and true—the laws of motion do hold there. The common fallacy is imagining the air particles reflecting of the underside of the wing like balls bouncing off a wall. Which at crude approximation works for explaining post-stall lift, but does nothing to explain why the air above the wing is also deflected. Unfortunately explaining that is rather difficult (you have to bring in inertia and viscosity and bunch of other stuff).

"are misconceptions also taught in flight school":  Of course they are.  It wouldn't be a flight school if it didn't teach misconceptions.

@quietflyer: You probably didn't get the meaning of this question. I was not asking if misconceptions are mentioned and identified as such, but if they are used and identified as correct theories.

I can only speak on behalf of the Australian Syllabus as put out by CASA (Civil Aviation Safety Authority - Australia), but we are expected to teach both Bernoulli's Theorem, and the Theorem of Air Deflection (I believe this is the second theory you are talking about in regards to Newton's Laws).
BUT, we are also expected to teach these items as theories, not laws, as there is no law on the creation of lift. So to a degree, you could say we do teach misconceptions, but also at the same time we openly acknowledge those misconceptions to those we are teaching.
The other part we openly admit is that both theories have merit to at least help understand certain important characteristics of Aerodynamics in-flight, great example is a stall. We have the Centre of Pressure that moves further forward along the Wing Chord as the Angle of Attack is increased, due to the "peak" of dynamic air pressure being more forward along the wing chord. At the "Critical Angle" in is at its most forward position. As soon as we exceed the Critical Angle, the wing is stalled and instantaneously, the Centre of Pressure moves aft along the chord line to a position approximately half way along the chord due to Bernoulli's theorem no longer having the principle effect on our wing. Now the theorem of air deflection takes over, and we look at using the "hand out the window of a moving car" analogy.

Could you make it clearer what you're referring to when you say Bernoulli's Theorem and teach these items as theories, not laws?  Bernoulli's Principle (an increase in fluid speed means a decrease in fluid pressure) simply describes a physical reality; it's not really a theory.

@SteveV. - The theorem is how this applies to an aircraft Aerofoil, as there is not a physical venturie. The principle is solid, and at no stage in doubt, but how this applies to a wing, and the overall production of Lift is still only a Theorem. As for your answer below, this may be the case with the FAA syllabus, but other countries, such as Australia, it is a requirement that all PPL applicants have a basic understanding of how Lift is generated, and for CPL applicants, there must be a good understanding of how Lift is generated (at least the Theorems associated).

You seem to misunderstand what a theorem is (it's a proven result of mathematics) and what a scientific theory is (it's an experimentally verified explanation of how the world works). A scientific "law" is just a scientific theory that is so old and famous that it has a fancier name. To say "we teach these as theories not laws" is a huge misunderstanding of what science is.

And a "law" doesn't even mean it's more complete or accurate than a "theory." Consider the law of gravity, which has been superseded by the theory of relativity.

By "Bernoulli's Theorem", do you mean equal transit time or something else (because Bernoulli's theorem obviously holds around the wing; it just leaves too many free variables and fixing them by assuming equal transit time is the error)? And by "Theorem of Air Deflection" do you mean the reflecting bullets or something else (because air is deflected downwards; it is just the idea that it is because the particles hit the underside and reflect like balls bouncing off a wall that is wrong)? If you mean these, how do you explain stall? If you don't, please clarify what you mean.

I am a CFI who teaches at a large (+200 students) flight school in the United States.  You might be surprised to hear this, but...
We really don't worry about how a wing works that much.
As far as I'm concerned, the technical explanation for how a wing works is a subject for the engineers who build and design such things.  Private pilot applicants (at least all of the ones that I have met) are more concerned with things like "How do I get the plane into the air??" and "What do I do if it starts coming back down again in a hurry?"
In fact, Van Sickle's Modern Airmanship starts off the chapter on aerodynamics by saying (paraphrased):

Some of the concepts presented in this chapter are wrong, but they are useful illustrations.

So, to answer your question, we teach that:

The alignment of the wing to the relative wind displaces air downward, which creates lift.
Because of the shape of the airfoil, air on top of the wing has a lower pressure than air below the wing, which also causes lift.

And unless a student asks us for more information, we leave it at that.
If you hope to become an aircraft designer or research fluid dynamics, you'll quickly be corrected of any misconceptions you may have about Mr. Bernoulli and his asymmetric wing.  Most student pilots, however, are satisfied with a pre-discussion "What we'll talk about today isn't technically correct, but you'll find it a lot easier to understand the necessary concepts this way."

Peter Kämpf made a worthwhile comment:

It is really not so hard to understand aerodynamics correctly, and you
make it sound as if you prefer a short term gain over a profound basis
which could help pilots to really understand what happens with their
plane and to select the most appropriate action.

Which is very true - it's not difficult to understand aerodynamics correctly.  I'll defend my viewpoint with an analogy:  Consider a store where you are shopping with a child who doesn't yet understand decimal addition.  You have two purchases, one costing $5.08 and one costing $3.99.  The child adds the big numbers and tells you that the final price will be $8. You now have (at least) two choices: you could begin a discussion of significant figures and fractional multiplication (can't forget tax!), or you could praise the child for applying the skills they do have and getting an answer which is pretty close.
Is it better if the child eventually understands how to calculate tax rather than simply trusting what the cashier reads off the screen?  Of course.  But at the stage where most of my students are, it's much more valuable to their development as pilots to simply praise them for being close enough.
As regards JAL123, I am in 100% agreement with you.  By the time you as a pilot have progressed sufficiently in your development to be flying something with a turbine pushing it, you should certainly know the principles and concepts of your machine to the highest degree of accuracy.

It is really not so hard to understand aerodynamics correctly, and you make it sound as if you prefer a short term gain over a profound basis which could help pilots to really understand what happens with their plane and to select the most appropriate action.

@PeterKämpf: It depends on which level of understanding you need. For pilot it's enough to know that the lift is proportional to square of indicated speed and angle of attack until some point where it decreases abruptly because stall happens. The common explanations don't help that, because they don't explain stall; I'd say just showing pictures of the streamlines should be enough.

JanHudec: Consider JAL123 - if the pilot had had a basic understanding of flight mechanics (and the influence of altitude on his brain functions), this accident could probably have been avoided. The plane was still somewhat controllable, flying on for one hour after the loss of most of its vertical tail. BTW: Stall is not the only thing a pilot needs to understand. But if he/she doesn't even have a basic grasp of aerodynamics, he/she is just a glorified bus driver.

@PeterKämpf even though no-one in sim was able to do better than the crew[1]?

@ratchet freak: A B-52H could be brought down safely in 1964 after losing its vertical tail. But the pilots used a different strategy, knowing that flying low improves directional stability. The Japanese crew was totally overwhelmed, and I think the other crews in the simulator were at the same level of education. Japanese education prefers rote learning, but if there is no procedure, they have no means of developing a new, successful strategy.

@PeterKämpf that B52 still have aileron+elevator control; while JAL123 didn't (only engine diff-thrust)

@ratchetfreak: ... and elevator trim. How else could they compensate for the missing mass of the vertical? Admitted, the plane was marginally flyable, but at the chosen altitude less than at lower altitude. That is my main point - the pilots did not know how to help themselves.

@PeterKämpf - I've expanded my answer to take into account your excellent comments.  Thanks very much!

@SteveV. Are you sure 2nd and 3rd links are correct? How do I get the plane into the air?? is linked to Money; and What do I do if it starts coming back down again in a hurry? is to Control.Unload Event.

@Farhan - Those are the intended link targets.  "What makes an airplane fly?  Money." is a well known joke among aviators in the USA, and "Unload for control" is a method of upset recovery.

@SteveV. Got it. I heard about the money relation with airplane flying but wasn't too sure if many pilots are .NET programmers in their free time.

B-52H link by @Peter Kämpf  went bad, I found good link here: B52-H landed with no tail

@ratchetfreak In case you're interested, I notice that on 2 June 2017, for some reason, someone saw fit to delete the story about the simulations from the Wikipedia page you linked: https://en.wikipedia.org/w/index.php?title=Japan_Airlines_Flight_123&type=revision&diff=783502803&oldid=783497475

Something is bad with you links - e. g. your 2nd link "How do I get the plane into the air??" points to Money in Wikipedia, and your 3rd link, What do I do if it starts coming back down again in a hurry? points to Microsoft .NET Framework function :-(

I was taught at Civil Air Patrol flight school in 1958 that the Bernoulli effect was the only way that a wing generates lift. I don't remember what our textbook was except that it was also used by the USAF. Our instructors obviously felt that this fact was not vital, and it appeared on no exams. As Steve V. says, we really didn't worry about how a wing works.
A model airplane builder in our town flew a craft that was nothing more than a flat metal disk plus an engine, rudder, and elevons. It had a very long takeoff roll and was a beast to fly, but it was clearly flying the wing and not just hanging on its prop. It was, in fact, a 25" enameled steel Texaco Gas sign. No Bernoulli effect was possible.
Also, we had seen many technical drawings of early Wright, Santos-Dumont, and Curtis aircraft, all with flat or curved wings of constant thickness over practically the whole chord. Clearly these aircraft did not generate a Bernoulli differential. We had lots of evidence that Bernoulli was not necessary for heavier-than-air flight.
So I would say that this misconception was taught in some flight schools in 1958, but it did little actual harm. Students who wanted to just fly ignored it and got on with just flying. Students who were interested in aeronautical science already knew not to accept any such simple explanation where fluid dynamics is concerned.

The whole 1990s controversy started because Dr. Klaus Weltner tried to get the "transit time" stuff removed from European cert. exams.  Also I note that thin flat "barn doors" fly entirely by Bernoulli Effect.  See JS Denker's physics page, showing that the air flows much faster over the top than the bottom.  http://www.av8n.com/how/htm/airfoils.html#sec-circulation   (And, "Bernoulli Explanation" is not about camber, or about thick wings.  The Wright Flyer had canvas wings where the upper and lower paths were the same, yet still the air flowed much faster over the top.)

I would like to add my $.02 to this question. Lift is defined (in the aerodynamic texts) as the upward component of the force that the air exerts on the wing. The force is composed of the tangential (sheer) forces that tend to contribute mostly to drag, as well as the pressure (normal) forces that tend to contribute to lift. As for designing the most efficient wing, the answer is trial and error. Hundreds of different mathematically-defined airfoils are put into a wind tunnel and their lift and drag coefficients are measured. They are then published in a book like this one for future aerospace engineers to decide which airfoil best suits their purpose. The question as to why the pressure happens to be lower on the top compared to the bottom of the wing is not really that important. Heaps of empirical data show that it is the observed phenomena, and we work with it from there, as unsatisfying as that may be.

I beg to differ! Empirical work is needed in fields like medicine where we understand too little to make logical conclusions, but aerodynamics is really well understood so deductive reasoning gets you to the best result more quickly. Also, you fail to answer the original question, which is whether wrong concepts are still taught in flight school. Maybe you want to add to your answer in order to improve it.

I agree that aerodynamics is well understood, but just because it is well understood does not mean that you do not benefit immensely from empirical data. As for the original question, the way I learned it is that air flows faster over the top, leading to less pressure, leading to an upward 'pull' on the wing. The curvature of the wing allows for this to happen. As for Bernoulli/Newton, etc, they dont seem to describe this relationship between wing shape and lift, which is why it is unsatisfying for me. OTOH the lift coeff, which seems to relate the 2, is found mainly through empirical tests.

I agree that having looked at a lot of empirical data will give you an intuitive "feel" for what is right. But not understanding the underlying physics behind it robs you of the capability to extend this knowledge to new situations. Then you are in a similar position to a pilot trained in Japan: You are excellent at performing well-trained procedures, but if something happens which you did not train in advance, you are helpless.

The actual question is "Is it taught this way in flight schools".  This answer doesn't seem to address the question.


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Why did BA 199 fly a missed approach followed by circles?
I just saw G-YMML (operating as BA 199) execute a missed approach and make weird circles. What is happening here? (FlightAware permalink)

https://thebasource.com/british-airways-b777-200er-g-ymml-ba199-hyderabad-diversion/ says it eventually diverted to Hyderabad, then flew to Mumbai later. But it does not state the reason. Trawling the site of DCGA or AIB might return something more, but it's harder to search.

source: Stack Exchange

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sort: votes


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What is the working principle of VFG
How does the VFG make various frequencies? And while it makes the other value of frequency, how the generator apply consistent 400Hz to the other component?

What is VFG? Google brings up too many hits.

Does this previous answer help?  https://aviation.stackexchange.com/questions/36981/how-does-the-a350-380-operate-on-variable-frequency-ac-generators

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What is this old biplane on a float?
I'm hoping for some help in identifying the plane in these two photographs I found in my father's collection.

Was he old enough to have taken them, or do you believe they were passed on to him already? In any case, it might help to add the general location where it most likely was taken (if not known, maybe you can narrow it down - e.g. which part of the world was your father based/travelled in).

Thanks for taking time to ask the questions. He didn't take the photos. I imagine he bought them at a flea market.

It looks a lot like a variant or a copy of the Curtiss Model E (aka Curtiss A1) from 1912:

There is a youtube video of it flying in 2011.

Hmm. Close... but I think the tail and some of the struts are different.

I agree. That’s why I said “variant or copy”. It could be a prototype too...

Indeed. Could be. Or maybe they ran out of square wood for the rudder. :)

Clearly Curtiss, though; Glen was the inventor of ailerons (as opposed to wing warping for roll control).


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Why does fuel consumption decrease with increasing aircraft altitude?
I have a chart where the thrust ($F$) and the thrust-specific fuel consumption (TSFC) are plotted against the aircraft flying speed, for several altitudes (i.e. sea level, 3000 meters and 11000 meters). This is for a generic turbojet.

I don't know the source of the image, I apologize for that.
At the left, we see that the thrust decreases with altitude. At the right, we observe that the TSFC actually decreases with altitude as well.
However, I think this is counter-intuitive. I understand that $F$ decreases with altitude, since density (and therefore mass flow rate) decreases when the airplane goes up.
What I don't understand is that the TSFC, defined as: $$\text{TSFC}\equiv\dfrac{\text{fuel mass flow rate}}{F}$$ decreases with altitude. In other words, the higher we fly, the more thermodynamically-efficient the airplane is. How does that happen?
From a pure mathematical point of view, it doesn't make sense that TSFC decreases with altitude since, following the aforementioned formula, $F$ is decreasing, which leads me to think that the fuel mass flow rate diminishes with altitude faster than thrust.
In a nutshell: why does the TSFC decreases with the flying altitude, having the last equation into consideration?

This answer should answer most of it.

That's a great answer (thanks for linking it), but I was most likely looking a mathematical answer, considering the equation I posted before. I'd like @PeterKampf to chime in and shed some light here!

Hi Jose, this is applied thermodynamics. As usual, Wikipedia has plenty of formulas. I linked to the Carnot cycle; the Brayton cycle is just a special case and its Wikipedia article has fewer formulas.

I can't provide the math, but yes, this is correct. Fuel flow decreases as air density decreases. The engine becomes more efficient because of the greater temperature differential between inlet and exhaust gases combined with the lower fuel flow.

Hey Nate. In order to accept this answer, could you please elaborate more on it at least a bit? You don't need to use maths, a pure "textual" answer will work. Maybe you can provide a chart along with a bit more information?

I'll have to dig through some reference books and see if I can't find something more useful. I'll get back with you on it

Jose, here are some good references for more information on turbine engine efficiency at altitude:
This video for the maths: https://www.youtube.com/watch?v=E8VfieYhsjg

This wikipedia article may help you to briefly understand the brayton cycle efficiency of gas turbines: https://en.wikipedia.org/wiki/Thermal_efficiency
And lastly, check out this guys post on the airline pilot's forum about Jet engine efficiency. It's not deep but you may find his notes helpful: http://www.theairlinepilots.com/forum/viewtopic.php?t=476
Hope that helps

By efficiency are you referring to thermal efficiency?  (It's been over 30 years since my Compressible Flow class, vague memories of that needing to be specified ...)

To clarify a bit, the engines are designed for cruise altitude and thus must be artificially limited at low altitudes to avoid exceeding temperature and stress limits. At high altitude both the reduced mass flow and reduced inlet temperature allows an increase in inlet compression ratio [with associated relative temperature rise, and a static absolute temperature limit].

I was trying to solve the same question of this topic and I arrived here, I see that this is an old post but but maybe I can contribute a little.
Let's work in the formula quoted by Jose:

Then, according to the formula described in nasa's web page (https://www.grc.nasa.gov/www/k-12/airplane/fuelfl.html) we know that:

If the difference between Tt4 and Tt3 increase, this when the altitude increase, then "f" increase and also TSFC.
I don't have specific values for providing and example, I know that the fuel heating value "Q" is well-known but I don't have the others terms' values.
I hope this could help a little to find the math explanation for the answer.

Gas turbine engine works more efficiently at higher altitudes
Altitude increases - Air density reduces - Mass flosw reduces - Maximum thrust reduces.
To maintain thrust as altitude increases - Compressors must rotate faster.
Hight altitude - Less air density - Lesser resistance - Less fuel required to spin the compressor faster.
There is an optimum altitude in reference to speed and thrust which increases as weight reduces.
Altitude increase - Maintaining a constant TAS - Reduction in fuel flow and SFC from sea level up to the optimum altitude. for more information visit http://www.theairlinepilots.com/forum/viewtopic.php?t=476

You've not mentioned that turbine engines are more efficient in lower temperatures.

Multiple parameters have a role in this, but high altitudes are not the best operating conditions in general for an engine: see hot and high tests, but are the best for an aircraft !
High altitude means
 - less thrust because of lower air density
 - less power in the gas generator due to less oxygen density
 - far less losses from air resistance to the fuselage

Less oxygen is present at higher altitudes, so not decreasing the fuel flow during climb will eventually throw the air to fuel mixture so far out of balance that the engine will run rough or even shut down or flame out. By definition you will get better fuel economy at higher altitudes but I would not say it is "more efficient" due to the significant reduction in power that can actually be developed due to the lack of oxygen. Any engine will produce more power as a direct result of fuel burn and maximum available oxygen at sea level. However, in jet engines one must take into account EGT temperature differentials and the resulting expansion of exhaust gases that do produce additional thrust dependent on greater temperature differences.

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Can you help me ID these two helicopters?

Hey folks! Desperate to find what these two helicopters are. Any help greatly appreciated!!

Where and when did you see them?

Let’s say SE Asia. Sorry, can’t be more specific.

I’m thinking the one on the left is a PZL W13 Sokol and no idea about the one on right.

Oh and it was within the last week.

@AB You mean the one onf the left is a PZL W13 Sokol, I assume?

There aren't many helicopters with six-bladed rotors. The Sikorsky MH-53 is one, though they've been out of service for a while; other variants are still in use.

I said the left in my original post, but I said W13 by mistake, I meant W-3. :)

Good catch David about the six blades. Tks. Because of the pointer nose, doesn’t look like a Pave Low to me. Or am I missing something?

@AB Yeah, it's not a Pave Low: it's missing the refuelling boom on the nose and the thingummyjigs (technical term) on the lower fuselage. And Pave Lows haven't flown in 11 years.

Fairly certain the one on the right is an Enstrom, they usually have a distinctive 3 blade rotor system.

Thanks Ron, looking it up after you say that, it does have a very similar shape.
Can anyone confirm/deny my thoughts that the one on the left is a Sokol W-3?  I know the country where they were seen flying is supposed to have them in their arsenal..

That would be the first W-3 with retractable landing gear.

That's ultimately where I was leaning, especially since the country in question has purchased them in the past. Thanks Peter.

The right one is much easier for me to identify, and I am quite sure it is an AS-355 (the two-turbine version of the AS-350).

My guess is an AW139 on the left and the AS355 on the right. Both are very widely produced models.

I think the left one has six main rotor blades, whereas the AW139 (and 149, for that matter) have five? If it’s just five, though, the AW149 might also be a contender, with Thai Army apparently being a prime user.

Thanks fooot and Cpt Reynolds.  The shape/sihouette seem to fit with a AW139/149 but I'm unaware of the country (not Thailand) having purchased any though they're notoriously secretive, so it could be. But I'm trying to see now if they have a capacity to mount weaponry

I fully agree with the AS-355 on the right, but am less sure about the left one.

I agree about the left one. Not many options with 6 blades, and it doesn't look to be in military colors. It could be just 5 blades and the AW139 seemed to be the best match.

I do now wonder whether it’s a Mi-24 or derivative.


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Are there any reported/documented cases of unintended transport of birds within planes (freight compartment, cargo planes)
I am currently working on the unintentional transport of birds and have come across the possibility that small birds, e.g. sparrows, could be unintentionally transported by aircraft. This could be due to their life in close proximity to humans (including airports), their small size and the fact that House Sparrows in particular regularly fly inside buildings.
I haven't found any reports of this yet, but there have been sightings of sparrows at remote airstrips, far from road access. Are there any documented cases? I think it's unlikely on international passenger flights, but perhaps more likely on less-controlled domestic flights, military or civilian cargo flights.
Many thanks.

Of course I'm sure you are well aware that snakes have been unintentionally transported in landing gear bays --

I'd be a little doubtful if there is any report to be made in most cases.  Okay, some sparrow flew inside the C-17 shortly before they closed it up. Probably spent the flight sitting on top of the highest piece of cargo, and flew away at some point after the cargo door opened and everything was unloaded. So? I rather doubt that military loadmasters have an "inadvertent bird transport report" form that they might fill out - although there is at least one reference to a Hazardous Chicken Road Crossing Report.

Yes, there are. For instance, see this report from The Aviation Herald:

An Air India Express Boeing 737-800, [...], was enroute at FL370 over the Arabian Sea when a live bird was noticed in the cockpit.
India's DGCA reported the bird was noticed when the glove department at the first officer's side was opened. An investigation has been opened, it appears a ground handling lapse had occurred at the remote station.


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What is this aircraft from the TV series "Fear the Walking Dead"?

Still from Fear the Walking Dead of unknown cargo plane

According to the Internet Movie Plane Database, this plane is part of Ep. 5.08 Is Anybody Out There? and is a Short SC.7 Skyvan as you already found:

Approximately the same view as in your question:

Source: airliners.net, photo by Szécsi Péter.

That appears to be a Short C-23 Sherpa. Smallish cargo aircraft, operated by many entities, incl the USAF and US Army.
https://en.wikipedia.org/wiki/Short_C-23_Sherpa

Thanks for the help. Researching I think it's a Short SC.7 Skyvan, from the C-23 was developed.

https://en.wikipedia.org/wiki/Short_SC.7_Skyvan

Given that image, the exact version is likely unknowable. But it is some variant of the common Skyvan platform or a derivative.

Not enough fuselage windows for a C-23, surely?

AKA, the flying Winnebago. Is that an airplane or the box it came in?

@MichaelHarvey Yeah, and IMHO more obviously the nose of the C-23 is way too pointy.

And all the way from Northern Ireland I think?

Yep, an Irish aircraft. Who knew?


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How can I parse this raw radar file (extension .cdr) given to me from the FAA?
I recently received some radar data from the FAA. Both files were formatted with the .cdr file extension, however these are not CorelDraw files. They seem to be binary files with some ASCII text metadata.
Both files correspond to the same date/time location as requested. It's about 3 hours of data. One is from the SBA, the other is from SCT. Both of these are TRACON sites.
I've done a hex dump of the first 400 lines of the data below. I don't see any open source programs that immediately know how to handle this data, does anyone know how I might be able to parse the data into a viewable format?
hexdump -C SBA-17JUL24_0200-0500Z.cdr | head -n 400
00000000  53 49 54 45 20 20 20 20  20 20 20 20 20 20 20 20  |SITE            |
00000010  20 20 41 41 41 0a 53 54  41 52 54 20 44 41 54 45  |  AAA.START DATE|
00000020  20 41 4e 44 20 54 49 4d  45 20 49 4e 20 42 4f 54  | AND TIME IN BOT|
00000030  48 20 47 4d 54 20 41 4e  44 20 53 59 53 54 45 4d  |H GMT AND SYSTEM|
00000040  20 54 49 4d 45 3a 0a 20  20 20 20 20 20 53 59 53  | TIME:.      SYS|
00000050  54 45 4d 20 54 49 4d 45  3a 31 37 2d 4a 55 4c 2d  |TEM TIME:17-JUL-|
00000060  32 30 32 34 20 30 31 3a  35 37 3a 30 30 2e 30 30  |2024 01:57:00.00|
00000070  32 0a 20 20 20 20 20 20  47 4d 54 20 54 49 4d 45  |2.      GMT TIME|
00000080  3a 20 20 20 31 37 2d 4a  55 4c 2d 32 30 32 34 20  |:   17-JUL-2024 |
00000090  47 30 31 3a 35 37 3a 30  30 2e 30 30 32 0a 53 59  |G01:57:00.002.SY|
000000a0  53 54 45 4d 20 49 4e 46  4f 3a 0a 20 20 20 20 20  |STEM INFO:.     |
000000b0  20 53 59 53 54 45 4d 20  49 44 3a 53 59 53 31 20  | SYSTEM ID:SYS1 |
000000c0  0a 20 20 20 20 20 20 53  45 52 56 49 43 45 20 4c  |.      SERVICE L|
000000d0  45 56 45 4c 3a 46 53 20  0a 20 20 20 20 20 20 4d  |EVEL:FS .      M|
000000e0  4f 44 45 3a 20 20 20 20  20 20 20 4e 6f 72 6d 61  |ODE:       Norma|
000000f0  6c 0a 53 4f 46 54 57 41  52 45 3a 20 20 20 20 20  |l.SOFTWARE:     |
00000100  20 20 20 20 73 36 2e 30  30 72 31 30 61 2e 30 33  |    s6.00r10a.03|
00000110  5f 30 31 31 31 32 34 5f  66 73 5f 73 77 5f 62 75  |_011124_fs_sw_bu|
00000120  69 6c 64 2e 62 6c 5f 61  32 2c 0a 20 20 20 20 20  |ild.bl_a2,.     |
00000130  20 20 20 20 20 20 20 20  20 20 20 20 20 73 36 2e  |             s6.|
00000140  30 30 72 31 30 61 2e 30  33 5f 30 31 31 31 32 34  |00r10a.03_011124|
00000150  5f 66 73 5f 73 65 6e 73  69 73 5f 73 77 5f 62 75  |_fs_sensis_sw_bu|
00000160  69 6c 64 2e 62 6c 5f 61  32 0a 41 44 41 50 54 41  |ild.bl_a2.ADAPTA|
00000170  54 49 4f 4e 3a 20 20 20  20 20 20 20 73 62 61 5f  |TION:       sba_|
00000180  72 31 30 61 64 33 5f 79  37 5f 31 30 61 5f 61 64  |r10ad3_y7_10a_ad|
00000190  5f 59 37 31 30 41 2e 62  6c 5f 65 33 0a 43 48 45  |_Y710A.bl_e3.CHE|
000001a0  43 4b 53 55 4d 20 42 4b  57 44 3a 32 33 37 33 37  |CKSUM BKWD:23737|
000001b0  38 35 36 20 20 20 20 20  20 20 0a 50 41 52 54 49  |856       .PARTI|
000001c0  54 49 4f 4e 3a 46 53 4c  41 0a 00 00 00 00 00 00  |TION:FSLA.......|
000001d0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
000fa000  6c 69 62 6e 6f 73 5f 6c  69 62 2e 73 6f 00 00 00  |libnos_lib.so...|
000fa010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
000fa060  00 00 00 00 30 30 30 30  37 37 35 00 30 30 32 33  |....0000775.0023|
000fa070  36 34 32 00 30 30 30 32  31 37 36 00 30 30 30 30  |642.0002176.0000|
000fa080  32 34 32 36 30 35 34 00  31 34 35 34 37 36 32 37  |2426054.14547627|
000fa090  36 34 37 00 30 30 31 34  33 32 30 00 30 00 00 00  |647.0014320.0...|
000fa0a0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
000fa100  00 75 73 74 61 72 00 30  30 63 68 6f 61 6e 67 00  |.ustar.00choang.|
000fa110  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fa120  00 00 00 00 00 00 00 00  00 73 74 61 72 73 00 00  |.........stars..|
000fa130  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fa140  00 00 00 00 00 00 00 00  00 30 30 30 30 34 37 36  |.........0000476|
000fa150  00 30 30 30 30 30 34 32  00 00 00 00 00 00 00 00  |.0000042........|
000fa160  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
000fa200  7f 45 4c 46 01 01 01 06  01 00 00 00 00 00 00 00  |.ELF............|
000fa210  03 00 03 00 01 00 00 00  c8 10 02 00 34 00 00 00  |............4...|
000fa220  1c 28 0a 00 00 00 00 00  34 00 20 00 04 00 28 00  |.(......4. ...(.|
000fa230  1a 00 19 00 fd ff ff 6f  b4 00 00 00 b4 00 00 00  |.......o........|
000fa240  00 00 00 00 10 00 00 00  10 00 00 00 04 00 00 00  |................|
000fa250  00 00 00 00 01 00 00 00  00 00 00 00 00 00 00 00  |................|
000fa260  00 00 00 00 17 37 03 00  17 37 03 00 05 00 00 00  |.....7...7......|
000fa270  00 00 01 00 01 00 00 00  18 37 03 00 18 37 04 00  |.........7...7..|
000fa280  00 00 00 00 c0 66 00 00  30 e1 02 00 07 00 00 00  |.....f..0.......|
000fa290  00 00 01 00 02 00 00 00  c4 00 00 00 c4 00 00 00  |................|
000fa2a0  00 00 00 00 00 01 00 00  00 00 00 00 07 00 00 00  |................|
000fa2b0  00 00 00 00 01 00 00 00  01 00 00 00 00 00 00 00  |................|
000fa2c0  00 00 00 00 01 00 00 00  34 28 00 00 0c 00 00 00  |........4(......|
000fa2d0  30 2c 03 00 0d 00 00 00  4c 2c 03 00 04 00 00 00  |0,......L,......|
000fa2e0  c4 01 00 00 05 00 00 00  a8 40 00 00 0a 00 00 00  |.........@......|
000fa2f0  82 2a 00 00 06 00 00 00  c8 16 00 00 0b 00 00 00  |.*..............|
000fa300  10 00 00 00 f8 fd ff 6f  a3 ba 00 00 fe ff ff 6f  |.......o.......o|
000fa310  2c 6b 00 00 ff ff ff 6f  01 00 00 00 fa ff ff 6f  |,k.....o.......o|
000fa320  21 03 00 00 16 00 00 00  00 00 00 00 11 00 00 00  |!...............|
000fa330  d8 70 00 00 12 00 00 00  28 b3 00 00 13 00 00 00  |.p......(.......|
000fa340  08 00 00 00 10 00 00 60  b4 00 00 00 1e 00 00 00  |.......`........|
000fa350  04 00 00 00 fb ff ff 6f  00 00 00 00 19 00 00 60  |.......o.......`|
000fa360  00 02 00 00 1b 00 00 60  03 00 00 00 00 00 00 00  |.......`........|
000fa370  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
000fa3c0  00 00 00 00 a1 02 00 00  9e 02 00 00 00 00 00 00  |................|
000fa3d0  00 00 00 00 01 00 00 00  02 00 00 00 03 00 00 00  |................|
000fa3e0  00 00 00 00 00 00 00 00  06 00 00 00 07 00 00 00  |................|
000fa3f0  00 00 00 00 09 00 00 00  0a 00 00 00 0c 00 00 00  |................|
000fa400  0d 00 00 00 00 00 00 00  11 00 00 00 13 00 00 00  |................|
000fa410  16 00 00 00 18 00 00 00  19 00 00 00 1a 00 00 00  |................|
000fa420  1c 00 00 00 1d 00 00 00  00 00 00 00 1e 00 00 00  |................|
000fa430  00 00 00 00 00 00 00 00  00 00 00 00 1f 00 00 00  |................|
000fa440  00 00 00 00 00 00 00 00  20 00 00 00 00 00 00 00  |........ .......|
000fa450  00 00 00 00 00 00 00 00  21 00 00 00 23 00 00 00  |........!...#...|
000fa460  24 00 00 00 00 00 00 00  29 00 00 00 00 00 00 00  |$.......).......|
000fa470  2b 00 00 00 2c 00 00 00  2d 00 00 00 2f 00 00 00  |+...,...-.../...|
000fa480  32 00 00 00 34 00 00 00  00 00 00 00 00 00 00 00  |2...4...........|
000fa490  00 00 00 00 00 00 00 00  35 00 00 00 36 00 00 00  |........5...6...|
000fa4a0  00 00 00 00 00 00 00 00  37 00 00 00 39 00 00 00  |........7...9...|
000fa4b0  3c 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |<...............|
000fa4c0  3d 00 00 00 00 00 00 00  3f 00 00 00 41 00 00 00  |=.......?...A...|
000fa4d0  00 00 00 00 42 00 00 00  43 00 00 00 00 00 00 00  |....B...C.......|
000fa4e0  00 00 00 00 00 00 00 00  47 00 00 00 49 00 00 00  |........G...I...|
000fa4f0  4c 00 00 00 4e 00 00 00  50 00 00 00 52 00 00 00  |L...N...P...R...|
000fa500  00 00 00 00 00 00 00 00  53 00 00 00 55 00 00 00  |........S...U...|
000fa510  00 00 00 00 56 00 00 00  00 00 00 00 57 00 00 00  |....V.......W...|
000fa520  59 00 00 00 5b 00 00 00  00 00 00 00 5c 00 00 00  |Y...[.......\...|
000fa530  00 00 00 00 5d 00 00 00  5f 00 00 00 60 00 00 00  |....]..._...`...|
000fa540  00 00 00 00 61 00 00 00  00 00 00 00 00 00 00 00  |....a...........|
000fa550  00 00 00 00 62 00 00 00  00 00 00 00 00 00 00 00  |....b...........|
000fa560  65 00 00 00 67 00 00 00  69 00 00 00 6a 00 00 00  |e...g...i...j...|
000fa570  6b 00 00 00 00 00 00 00  6d 00 00 00 00 00 00 00  |k.......m.......|
000fa580  6e 00 00 00 00 00 00 00  6f 00 00 00 00 00 00 00  |n.......o.......|
000fa590  00 00 00 00 70 00 00 00  72 00 00 00 00 00 00 00  |....p...r.......|
000fa5a0  74 00 00 00 00 00 00 00  76 00 00 00 79 00 00 00  |t.......v...y...|
000fa5b0  7b 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |{...............|
000fa5c0  7c 00 00 00 7f 00 00 00  00 00 00 00 80 00 00 00  ||...............|
000fa5d0  81 00 00 00 82 00 00 00  83 00 00 00 00 00 00 00  |................|
000fa5e0  84 00 00 00 85 00 00 00  00 00 00 00 87 00 00 00  |................|
000fa5f0  8a 00 00 00 8b 00 00 00  00 00 00 00 00 00 00 00  |................|
000fa600  8c 00 00 00 8e 00 00 00  90 00 00 00 92 00 00 00  |................|
000fa610  00 00 00 00 93 00 00 00  95 00 00 00 00 00 00 00  |................|
000fa620  97 00 00 00 00 00 00 00  98 00 00 00 99 00 00 00  |................|
000fa630  9a 00 00 00 00 00 00 00  9b 00 00 00 9c 00 00 00  |................|
000fa640  00 00 00 00 9e 00 00 00  00 00 00 00 a0 00 00 00  |................|
000fa650  a1 00 00 00 00 00 00 00  a2 00 00 00 a3 00 00 00  |................|
000fa660  00 00 00 00 00 00 00 00  a5 00 00 00 00 00 00 00  |................|
000fa670  a6 00 00 00 00 00 00 00  a8 00 00 00 ab 00 00 00  |................|
000fa680  00 00 00 00 ac 00 00 00  00 00 00 00 00 00 00 00  |................|
000fa690  ae 00 00 00 af 00 00 00  00 00 00 00 00 00 00 00  |................|
000fa6a0  b0 00 00 00 00 00 00 00  b2 00 00 00 b3 00 00 00  |................|
000fa6b0  b4 00 00 00 b5 00 00 00  b6 00 00 00 b8 00 00 00  |................|
000fa6c0  ba 00 00 00 bd 00 00 00  00 00 00 00 00 00 00 00  |................|
000fa6d0  00 00 00 00 00 00 00 00  bf 00 00 00 c0 00 00 00  |................|
000fa6e0  c2 00 00 00 c4 00 00 00  c5 00 00 00 00 00 00 00  |................|
000fa6f0  00 00 00 00 00 00 00 00  c8 00 00 00 c9 00 00 00  |................|
000fa700  00 00 00 00 ca 00 00 00  00 00 00 00 00 00 00 00  |................|
000fa710  00 00 00 00 cb 00 00 00  cc 00 00 00 ce 00 00 00  |................|
000fa720  cf 00 00 00 d0 00 00 00  00 00 00 00 00 00 00 00  |................|
000fa730  d2 00 00 00 d3 00 00 00  00 00 00 00 d5 00 00 00  |................|
000fa740  d6 00 00 00 d7 00 00 00  d9 00 00 00 da 00 00 00  |................|
000fa750  db 00 00 00 00 00 00 00  00 00 00 00 dc 00 00 00  |................|
000fa760  de 00 00 00 e0 00 00 00  e1 00 00 00 e2 00 00 00  |................|
000fa770  e3 00 00 00 e4 00 00 00  00 00 00 00 e5 00 00 00  |................|
000fa780  00 00 00 00 00 00 00 00  e6 00 00 00 e8 00 00 00  |................|
000fa790  00 00 00 00 00 00 00 00  eb 00 00 00 00 00 00 00  |................|
000fa7a0  00 00 00 00 ed 00 00 00  00 00 00 00 00 00 00 00  |................|
000fa7b0  ee 00 00 00 00 00 00 00  f1 00 00 00 f2 00 00 00  |................|
000fa7c0  f4 00 00 00 f7 00 00 00  00 00 00 00 fa 00 00 00  |................|
000fa7d0  fc 00 00 00 fe 00 00 00  00 01 00 00 05 01 00 00  |................|
000fa7e0  06 01 00 00 08 01 00 00  0a 01 00 00 00 00 00 00  |................|
000fa7f0  0b 01 00 00 0c 01 00 00  00 00 00 00 00 00 00 00  |................|
000fa800  0d 01 00 00 0f 01 00 00  10 01 00 00 00 00 00 00  |................|
000fa810  11 01 00 00 12 01 00 00  00 00 00 00 00 00 00 00  |................|
000fa820  13 01 00 00 14 01 00 00  00 00 00 00 00 00 00 00  |................|
000fa830  00 00 00 00 00 00 00 00  15 01 00 00 00 00 00 00  |................|
000fa840  17 01 00 00 00 00 00 00  00 00 00 00 18 01 00 00  |................|
000fa850  1b 01 00 00 1d 01 00 00  00 00 00 00 1e 01 00 00  |................|
000fa860  1f 01 00 00 00 00 00 00  21 01 00 00 23 01 00 00  |........!...#...|
000fa870  25 01 00 00 00 00 00 00  00 00 00 00 27 01 00 00  |%...........'...|
000fa880  28 01 00 00 00 00 00 00  2a 01 00 00 00 00 00 00  |(.......*.......|
000fa890  00 00 00 00 2c 01 00 00  2d 01 00 00 00 00 00 00  |....,...-.......|
000fa8a0  2e 01 00 00 2f 01 00 00  32 01 00 00 00 00 00 00  |..../...2.......|
000fa8b0  33 01 00 00 00 00 00 00  35 01 00 00 36 01 00 00  |3.......5...6...|
000fa8c0  38 01 00 00 3a 01 00 00  00 00 00 00 3b 01 00 00  |8...:.......;...|
000fa8d0  3c 01 00 00 00 00 00 00  3e 01 00 00 41 01 00 00  |<.......>...A...|
000fa8e0  00 00 00 00 00 00 00 00  42 01 00 00 44 01 00 00  |........B...D...|
000fa8f0  45 01 00 00 00 00 00 00  46 01 00 00 47 01 00 00  |E.......F...G...|
000fa900  00 00 00 00 49 01 00 00  4a 01 00 00 00 00 00 00  |....I...J.......|
000fa910  00 00 00 00 00 00 00 00  4c 01 00 00 00 00 00 00  |........L.......|
000fa920  00 00 00 00 4e 01 00 00  51 01 00 00 00 00 00 00  |....N...Q.......|
000fa930  52 01 00 00 00 00 00 00  53 01 00 00 54 01 00 00  |R.......S...T...|
000fa940  56 01 00 00 58 01 00 00  5a 01 00 00 00 00 00 00  |V...X...Z.......|
000fa950  00 00 00 00 5b 01 00 00  5d 01 00 00 5e 01 00 00  |....[...]...^...|
000fa960  00 00 00 00 5f 01 00 00  63 01 00 00 00 00 00 00  |...._...c.......|
000fa970  00 00 00 00 64 01 00 00  00 00 00 00 00 00 00 00  |....d...........|
000fa980  65 01 00 00 66 01 00 00  67 01 00 00 69 01 00 00  |e...f...g...i...|
000fa990  6a 01 00 00 00 00 00 00  00 00 00 00 6e 01 00 00  |j...........n...|
000fa9a0  70 01 00 00 72 01 00 00  00 00 00 00 73 01 00 00  |p...r.......s...|
000fa9b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fa9c0  00 00 00 00 00 00 00 00  74 01 00 00 75 01 00 00  |........t...u...|
000fa9d0  00 00 00 00 00 00 00 00  76 01 00 00 7a 01 00 00  |........v...z...|
000fa9e0  7c 01 00 00 7f 01 00 00  80 01 00 00 00 00 00 00  ||...............|
000fa9f0  81 01 00 00 82 01 00 00  83 01 00 00 00 00 00 00  |................|
000faa00  84 01 00 00 00 00 00 00  86 01 00 00 88 01 00 00  |................|
000faa10  00 00 00 00 00 00 00 00  00 00 00 00 89 01 00 00  |................|
000faa20  8b 01 00 00 8c 01 00 00  8f 01 00 00 90 01 00 00  |................|
000faa30  92 01 00 00 95 01 00 00  96 01 00 00 00 00 00 00  |................|
000faa40  00 00 00 00 97 01 00 00  9a 01 00 00 9b 01 00 00  |................|
000faa50  00 00 00 00 00 00 00 00  9c 01 00 00 9d 01 00 00  |................|
000faa60  9f 01 00 00 00 00 00 00  a2 01 00 00 a3 01 00 00  |................|
000faa70  a4 01 00 00 a6 01 00 00  00 00 00 00 00 00 00 00  |................|
000faa80  a7 01 00 00 a8 01 00 00  a9 01 00 00 ab 01 00 00  |................|
000faa90  ad 01 00 00 00 00 00 00  00 00 00 00 ae 01 00 00  |................|
000faaa0  00 00 00 00 af 01 00 00  b1 01 00 00 00 00 00 00  |................|
000faab0  b2 01 00 00 b3 01 00 00  b5 01 00 00 00 00 00 00  |................|
000faac0  00 00 00 00 b6 01 00 00  00 00 00 00 b7 01 00 00  |................|
000faad0  00 00 00 00 b9 01 00 00  00 00 00 00 00 00 00 00  |................|
000faae0  00 00 00 00 ba 01 00 00  00 00 00 00 bb 01 00 00  |................|
000faaf0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fab00  bd 01 00 00 be 01 00 00  00 00 00 00 c0 01 00 00  |................|
000fab10  00 00 00 00 00 00 00 00  00 00 00 00 c3 01 00 00  |................|
000fab20  c5 01 00 00 c6 01 00 00  c9 01 00 00 ca 01 00 00  |................|
000fab30  cc 01 00 00 ce 01 00 00  cf 01 00 00 d0 01 00 00  |................|
000fab40  00 00 00 00 d2 01 00 00  d3 01 00 00 d4 01 00 00  |................|
000fab50  d5 01 00 00 d7 01 00 00  d8 01 00 00 d9 01 00 00  |................|
000fab60  db 01 00 00 dd 01 00 00  de 01 00 00 00 00 00 00  |................|
000fab70  df 01 00 00 e0 01 00 00  e1 01 00 00 e4 01 00 00  |................|
000fab80  e6 01 00 00 e7 01 00 00  e8 01 00 00 ea 01 00 00  |................|
000fab90  ed 01 00 00 00 00 00 00  00 00 00 00 ee 01 00 00  |................|
000faba0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fabb0  00 00 00 00 00 00 00 00  00 00 00 00 ef 01 00 00  |................|
000fabc0  f1 01 00 00 f2 01 00 00  f3 01 00 00 f4 01 00 00  |................|
000fabd0  f5 01 00 00 f7 01 00 00  f9 01 00 00 00 00 00 00  |................|
000fabe0  fa 01 00 00 00 00 00 00  fb 01 00 00 fc 01 00 00  |................|
000fabf0  fd 01 00 00 fe 01 00 00  00 00 00 00 00 00 00 00  |................|
000fac00  00 00 00 00 00 02 00 00  01 02 00 00 02 02 00 00  |................|
000fac10  04 02 00 00 00 00 00 00  00 00 00 00 05 02 00 00  |................|
000fac20  06 02 00 00 00 00 00 00  07 02 00 00 08 02 00 00  |................|
000fac30  00 00 00 00 0c 02 00 00  0d 02 00 00 0e 02 00 00  |................|
000fac40  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fac50  10 02 00 00 11 02 00 00  00 00 00 00 12 02 00 00  |................|
000fac60  14 02 00 00 15 02 00 00  00 00 00 00 16 02 00 00  |................|
000fac70  18 02 00 00 1b 02 00 00  1d 02 00 00 1e 02 00 00  |................|
000fac80  21 02 00 00 22 02 00 00  26 02 00 00 27 02 00 00  |!..."...&...'...|
000fac90  28 02 00 00 2a 02 00 00  00 00 00 00 00 00 00 00  |(...*...........|
000faca0  00 00 00 00 00 00 00 00  00 00 00 00 2b 02 00 00  |............+...|
000facb0  2c 02 00 00 2e 02 00 00  30 02 00 00 00 00 00 00  |,.......0.......|
000facc0  31 02 00 00 32 02 00 00  33 02 00 00 34 02 00 00  |1...2...3...4...|
000facd0  35 02 00 00 36 02 00 00  37 02 00 00 3a 02 00 00  |5...6...7...:...|
000face0  00 00 00 00 00 00 00 00  3b 02 00 00 3c 02 00 00  |........;...<...|
000facf0  00 00 00 00 3d 02 00 00  3e 02 00 00 3f 02 00 00  |....=...>...?...|
000fad00  41 02 00 00 42 02 00 00  44 02 00 00 45 02 00 00  |A...B...D...E...|
000fad10  46 02 00 00 47 02 00 00  00 00 00 00 49 02 00 00  |F...G.......I...|
000fad20  4a 02 00 00 00 00 00 00  4c 02 00 00 4f 02 00 00  |J.......L...O...|
000fad30  50 02 00 00 51 02 00 00  00 00 00 00 52 02 00 00  |P...Q.......R...|
000fad40  53 02 00 00 55 02 00 00  56 02 00 00 57 02 00 00  |S...U...V...W...|
000fad50  00 00 00 00 58 02 00 00  59 02 00 00 5c 02 00 00  |....X...Y...\...|
000fad60  5d 02 00 00 62 02 00 00  63 02 00 00 64 02 00 00  |]...b...c...d...|
000fad70  67 02 00 00 6a 02 00 00  6c 02 00 00 00 00 00 00  |g...j...l.......|
000fad80  6d 02 00 00 00 00 00 00  6f 02 00 00 71 02 00 00  |m.......o...q...|
000fad90  00 00 00 00 00 00 00 00  72 02 00 00 74 02 00 00  |........r...t...|
000fada0  76 02 00 00 77 02 00 00  00 00 00 00 78 02 00 00  |v...w.......x...|
000fadb0  79 02 00 00 7b 02 00 00  7d 02 00 00 00 00 00 00  |y...{...}.......|
000fadc0  7e 02 00 00 7f 02 00 00  80 02 00 00 81 02 00 00  |~...............|
000fadd0  84 02 00 00 00 00 00 00  85 02 00 00 00 00 00 00  |................|
000fade0  89 02 00 00 00 00 00 00  8a 02 00 00 8c 02 00 00  |................|
000fadf0  00 00 00 00 8d 02 00 00  8e 02 00 00 00 00 00 00  |................|
000fae00  90 02 00 00 00 00 00 00  00 00 00 00 91 02 00 00  |................|
000fae10  94 02 00 00 95 02 00 00  96 02 00 00 97 02 00 00  |................|
000fae20  98 02 00 00 00 00 00 00  99 02 00 00 00 00 00 00  |................|
000fae30  00 00 00 00 9a 02 00 00  9b 02 00 00 00 00 00 00  |................|
000fae40  9c 02 00 00 9d 02 00 00  00 00 00 00 00 00 00 00  |................|
000fae50  00 00 00 00 00 00 00 00  00 00 00 00 04 00 00 00  |................|
000fae60  05 00 00 00 00 00 00 00  00 00 00 00 08 00 00 00  |................|
000fae70  00 00 00 00 00 00 00 00  0b 00 00 00 00 00 00 00  |................|
000fae80  00 00 00 00 0e 00 00 00  0f 00 00 00 10 00 00 00  |................|
000fae90  00 00 00 00 12 00 00 00  00 00 00 00 14 00 00 00  |................|
000faea0  15 00 00 00 00 00 00 00  17 00 00 00 00 00 00 00  |................|
000faeb0  00 00 00 00 00 00 00 00  1b 00 00 00 00 00 00 00  |................|
000faec0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000faed0  00 00 00 00 22 00 00 00  00 00 00 00 00 00 00 00  |...."...........|
000faee0  25 00 00 00 26 00 00 00  27 00 00 00 28 00 00 00  |%...&...'...(...|
000faef0  00 00 00 00 2a 00 00 00  00 00 00 00 00 00 00 00  |....*...........|
000faf00  00 00 00 00 2e 00 00 00  00 00 00 00 30 00 00 00  |............0...|
000faf10  31 00 00 00 00 00 00 00  33 00 00 00 00 00 00 00  |1.......3.......|
000faf20  00 00 00 00 00 00 00 00  00 00 00 00 38 00 00 00  |............8...|
000faf30  00 00 00 00 3a 00 00 00  3b 00 00 00 00 00 00 00  |....:...;.......|
000faf40  00 00 00 00 3e 00 00 00  00 00 00 00 40 00 00 00  |....>.......@...|
000faf50  00 00 00 00 00 00 00 00  00 00 00 00 44 00 00 00  |............D...|
000faf60  45 00 00 00 46 00 00 00  00 00 00 00 48 00 00 00  |E...F.......H...|
000faf70  00 00 00 00 4a 00 00 00  4b 00 00 00 00 00 00 00  |....J...K.......|
000faf80  4d 00 00 00 00 00 00 00  4f 00 00 00 00 00 00 00  |M.......O.......|
000faf90  51 00 00 00 00 00 00 00  00 00 00 00 54 00 00 00  |Q...........T...|
000fafa0  00 00 00 00 00 00 00 00  00 00 00 00 58 00 00 00  |............X...|
000fafb0  00 00 00 00 5a 00 00 00  00 00 00 00 00 00 00 00  |....Z...........|
000fafc0  00 00 00 00 5e 00 00 00  00 00 00 00 00 00 00 00  |....^...........|
000fafd0  00 00 00 00 00 00 00 00  63 00 00 00 64 00 00 00  |........c...d...|
000fafe0  00 00 00 00 66 00 00 00  00 00 00 00 68 00 00 00  |....f.......h...|
000faff0  00 00 00 00 00 00 00 00  00 00 00 00 6c 00 00 00  |............l...|
000fb000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb010  71 00 00 00 00 00 00 00  73 00 00 00 00 00 00 00  |q.......s.......|
000fb020  75 00 00 00 00 00 00 00  77 00 00 00 78 00 00 00  |u.......w...x...|
000fb030  00 00 00 00 7a 00 00 00  00 00 00 00 00 00 00 00  |....z...........|
000fb040  7d 00 00 00 7e 00 00 00  00 00 00 00 00 00 00 00  |}...~...........|
000fb050  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb060  00 00 00 00 86 00 00 00  00 00 00 00 88 00 00 00  |................|
000fb070  89 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb080  8d 00 00 00 00 00 00 00  8f 00 00 00 00 00 00 00  |................|
000fb090  91 00 00 00 00 00 00 00  00 00 00 00 94 00 00 00  |................|
000fb0a0  00 00 00 00 96 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb0b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb0c0  9d 00 00 00 00 00 00 00  9f 00 00 00 00 00 00 00  |................|
000fb0d0  00 00 00 00 00 00 00 00  00 00 00 00 a4 00 00 00  |................|
000fb0e0  00 00 00 00 00 00 00 00  a7 00 00 00 00 00 00 00  |................|
000fb0f0  a9 00 00 00 aa 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb100  ad 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb110  b1 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb120  00 00 00 00 00 00 00 00  b7 00 00 00 00 00 00 00  |................|
000fb130  b9 00 00 00 00 00 00 00  bb 00 00 00 bc 00 00 00  |................|
000fb140  00 00 00 00 be 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb150  c1 00 00 00 00 00 00 00  c3 00 00 00 00 00 00 00  |................|
000fb160  00 00 00 00 c6 00 00 00  c7 00 00 00 00 00 00 00  |................|
000fb170  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb180  cd 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb190  d1 00 00 00 00 00 00 00  00 00 00 00 d4 00 00 00  |................|
000fb1a0  00 00 00 00 00 00 00 00  00 00 00 00 d8 00 00 00  |................|
000fb1b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb1c0  dd 00 00 00 00 00 00 00  df 00 00 00 00 00 00 00  |................|
000fb1d0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb1e0  00 00 00 00 00 00 00 00  e7 00 00 00 00 00 00 00  |................|
000fb1f0  e9 00 00 00 ea 00 00 00  00 00 00 00 ec 00 00 00  |................|
000fb200  00 00 00 00 00 00 00 00  ef 00 00 00 f0 00 00 00  |................|
000fb210  00 00 00 00 00 00 00 00  f3 00 00 00 00 00 00 00  |................|
000fb220  f5 00 00 00 f6 00 00 00  00 00 00 00 f8 00 00 00  |................|
000fb230  f9 00 00 00 00 00 00 00  fb 00 00 00 00 00 00 00  |................|
000fb240  fd 00 00 00 00 00 00 00  ff 00 00 00 00 00 00 00  |................|
000fb250  01 01 00 00 02 01 00 00  03 01 00 00 04 01 00 00  |................|
000fb260  00 00 00 00 00 00 00 00  07 01 00 00 00 00 00 00  |................|
000fb270  09 01 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb280  00 00 00 00 0e 01 00 00  00 00 00 00 00 00 00 00  |................|
000fb290  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb2a0  00 00 00 00 16 01 00 00  00 00 00 00 00 00 00 00  |................|
000fb2b0  19 01 00 00 1a 01 00 00  00 00 00 00 1c 01 00 00  |................|
000fb2c0  00 00 00 00 00 00 00 00  00 00 00 00 20 01 00 00  |............ ...|
000fb2d0  00 00 00 00 22 01 00 00  00 00 00 00 24 01 00 00  |....".......$...|
000fb2e0  00 00 00 00 26 01 00 00  00 00 00 00 00 00 00 00  |....&...........|
000fb2f0  29 01 00 00 00 00 00 00  2b 01 00 00 00 00 00 00  |).......+.......|
000fb300  00 00 00 00 00 00 00 00  00 00 00 00 30 01 00 00  |............0...|
000fb310  31 01 00 00 00 00 00 00  00 00 00 00 34 01 00 00  |1...........4...|
000fb320  00 00 00 00 00 00 00 00  37 01 00 00 00 00 00 00  |........7.......|
000fb330  39 01 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |9...............|
000fb340  3d 01 00 00 00 00 00 00  3f 01 00 00 40 01 00 00  |=.......?...@...|
000fb350  00 00 00 00 00 00 00 00  43 01 00 00 00 00 00 00  |........C.......|
000fb360  00 00 00 00 00 00 00 00  00 00 00 00 48 01 00 00  |............H...|
000fb370  00 00 00 00 00 00 00 00  4b 01 00 00 00 00 00 00  |........K.......|
000fb380  4d 01 00 00 00 00 00 00  4f 01 00 00 50 01 00 00  |M.......O...P...|
000fb390  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb3a0  55 01 00 00 00 00 00 00  57 01 00 00 00 00 00 00  |U.......W.......|
000fb3b0  59 01 00 00 00 00 00 00  00 00 00 00 5c 01 00 00  |Y...........\...|
000fb3c0  00 00 00 00 00 00 00 00  00 00 00 00 60 01 00 00  |............`...|
000fb3d0  61 01 00 00 62 01 00 00  00 00 00 00 00 00 00 00  |a...b...........|
000fb3e0  00 00 00 00 00 00 00 00  00 00 00 00 68 01 00 00  |............h...|
000fb3f0  00 00 00 00 00 00 00 00  6b 01 00 00 6c 01 00 00  |........k...l...|
000fb400  6d 01 00 00 00 00 00 00  6f 01 00 00 00 00 00 00  |m.......o.......|
000fb410  71 01 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |q...............|
000fb420  00 00 00 00 00 00 00 00  77 01 00 00 78 01 00 00  |........w...x...|
000fb430  79 01 00 00 00 00 00 00  7b 01 00 00 00 00 00 00  |y.......{.......|
000fb440  7d 01 00 00 7e 01 00 00  00 00 00 00 00 00 00 00  |}...~...........|
000fb450  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb460  85 01 00 00 00 00 00 00  87 01 00 00 00 00 00 00  |................|
000fb470  00 00 00 00 8a 01 00 00  00 00 00 00 00 00 00 00  |................|
000fb480  8d 01 00 00 8e 01 00 00  00 00 00 00 00 00 00 00  |................|
000fb490  91 01 00 00 00 00 00 00  93 01 00 00 94 01 00 00  |................|
000fb4a0  00 00 00 00 00 00 00 00  00 00 00 00 98 01 00 00  |................|
000fb4b0  99 01 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb4c0  00 00 00 00 9e 01 00 00  00 00 00 00 a0 01 00 00  |................|
000fb4d0  a1 01 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb4e0  a5 01 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb4f0  00 00 00 00 aa 01 00 00  00 00 00 00 ac 01 00 00  |................|
000fb500  00 00 00 00 00 00 00 00  00 00 00 00 b0 01 00 00  |................|
000fb510  00 00 00 00 00 00 00 00  00 00 00 00 b4 01 00 00  |................|
000fb520  00 00 00 00 00 00 00 00  00 00 00 00 b8 01 00 00  |................|
000fb530  00 00 00 00 00 00 00 00  00 00 00 00 bc 01 00 00  |................|
000fb540  00 00 00 00 00 00 00 00  bf 01 00 00 00 00 00 00  |................|
000fb550  c1 01 00 00 c2 01 00 00  00 00 00 00 c4 01 00 00  |................|
000fb560  00 00 00 00 00 00 00 00  c7 01 00 00 c8 01 00 00  |................|
000fb570  00 00 00 00 00 00 00 00  cb 01 00 00 00 00 00 00  |................|
000fb580  cd 01 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb590  d1 01 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb5a0  00 00 00 00 d6 01 00 00  00 00 00 00 00 00 00 00  |................|
000fb5b0  00 00 00 00 da 01 00 00  00 00 00 00 dc 01 00 00  |................|
000fb5c0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb5d0  00 00 00 00 e2 01 00 00  e3 01 00 00 00 00 00 00  |................|
000fb5e0  e5 01 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000fb5f0  e9 01 00 00 00 00 00 00  eb 01 00 00 ec 01 00 00  |................|
000fb600  00 00 00 00 00 00 00 00  00 00 00 00 f0 01 00 00  |................|

Doesn't look like 400 lines is enough to actually get any real radar returns in it.

I can't find much documentation on the format. Can you upload the whole file?

@Chris Give me a few hours and I’ll upload the data to GitHub (or some public means of accessing it)

@Chris https://www.dropbox.com/scl/fi/eefw64genulajjpip80qt/SBA-17JUL24_0200-0500Z.cdr?rlkey=11uukk2lrwduvth79rrytzuu0&st=jo4dnpy0&dl=0 I'll leave this download link up for a few days

@Chris here's a different CDR file that's from the SCT radar https://www.dropbox.com/scl/fi/y2atodpqihemyz3unt90w/SCT-07-17-24_0200-0500z.cdr.gz?rlkey=ypwovgr2s5t6yvay23815iqvt&st=gbyz3q9x&dl=0 I'll leave this up for a few days

As far as I can tell, the format isn't publicly documented. Inspecting the binary file, the actual radar contacts appear to be ASCII text of fixed length. Example:

17:35:56 07/15/24  TRF1 N593TC    CXP  C208 7271 D SBA*NTH 1E 0MVI003+00029-00036 164 089

These records can be extracted using the Linux grep utility using the following command:
grep -Poa '([01][0-9]|2[0-3]):[0-5][0-9]:[0-5][0-9] (0[1-9]|1[0-2])/(0[1-9]|[12][0-9]|3[01])/[0-9][0-9].{73}$' input_filename.cdr | awk '!x[$0]++' > output_filename.txt
which extracts lines beginning with a UTC timestamp followed by 73 more characters. Each record appears in the file several hundred times and the awk command extracts only non-duplicates.
As for the actual format of the record, some of it is pretty clear. Some of it not so much. My best guesses so far:

Offset
Length
Field
Example

0
8
UTC Time
17:35:56

9
8
UTC Date
07/15/24

19
4
Unknown. Something like a type of return? CST indicates Coasting (no radar return) status. HND likely indicates handoff status.
TRF1

24
7
* Call sign
N593TC

34
3
* Scratchpad information. Often either destination or assigned runway; sometimes other mnemonic like PIX or JFA. *** indicates no scratchpad data.
CXP

39
4
* Type
C208

44
4
* Squawk code
7271

49
1
Arrival, Departure, or Enroute flight (relative to any airport in the facility's airspace)
D

51
7
Unknown, something about radar facility/data source maybe? Could also be entry/exit fixes.
SBA*NTH

59
2
* Owning TCP (control position, scope)
1E

61
2
Unknown. 1st is always either blank or C. 2nd is always 0.
0

63
1
* Minimum Safe Altitude Warning disabled. Near-certain discriminator between IFR and VFR target, although not 100% guaranteed.
M

64
1
* Special designator symbol. Blank for IFR arrival or departure. E for IFR overflight. V for VFR of any kind.
V

65
1
* Consolidated Wake Turbulence category (A-I).
I

66
3
* Flight level or altitude
003

69
12
Appears to be a position of some kind. Perhaps x and y coordinates?
+00029-00036

82
3
Probably course. It ranges from 0 to 359
164

86
3
* Ground speed
089

*Displayed to ATC on the scope (data block or target symbol)
This obviously isn't complete, but I'm posting it in case anyone else has any insights and so I don't accidentally close the tab and delete my partial answer!

Very nice. Added a couple clarifications. It would be helpful to see more of the grepped data, especially to see multiple different entries for the same track... unfortunately the version of grep I have on my machine doesn't like the command you used. Would you be able to upload your output.txt? Ideally without stripping out duplicates?

@randomhead The multiple different entries are all bitwise identical. They appear anywhere from once to 279 times each. There's a lot of binary data I haven't got around to looking at yet. Including what looks to be at least one embedded executable or library of some sort.

I see. Just scrolling through I can come across the various radar hits here and there and that's enough to add a little more info.

@randomhead Good call on ground speed. And the one before it looks to be the course.

This is not raw radar output but surveillancd data processing system / flight data processing system output. This aggregates data from multiple surveillance sensors and adds flight data such as VFR/IFR info, wake turbulence category etc. The 12 character azimuth/range field are likely X/Y position coordinates.

This is great! I actually another larger CDR from SCT that I haven't analyzed yet. I'm happy to upload and post if anyone wants to take a shot at it to see if the data is the same or different

SCT cdr file here's the link for the SCT CDR file https://www.dropbox.com/scl/fi/y2atodpqihemyz3unt90w/SCT-07-17-24_0200-0500z.cdr.gz?rlkey=ypwovgr2s5t6yvay23815iqvt&st=gbyz3q9x&dl=0 I'll leave this up for a few days

@likeabbas Data format looks the same. I see 14,186 unique records in the dataset using the same grep command above. (1,541,095 total records, so there's a lot of duplicates in there!)


text:
How close are aircraft allowed to get to each other mid-flight?
I was on an easyJet flight from Antalya to Manchester on the 20th September 2024, flight number 2142. I looked out of the window and saw a green and white coloured plane. I have looked it up and it was a condor airlines. The plane seemed very close to ours and didn’t seem to be over 1000 ft. It was approx 2 hours into the flight but that is a very loose guess. Should it have been that close?

This question is similar to: How much is the minimum safe distance between two planes in-flight?. If you believe it’s different, please edit the question, make it clear how it’s different and/or how the answers on that question are not helpful for your problem. -- The linked question is about FAA airspace specifically but there are other similar questions here already, e.g. this one which is about European airspace.

@randomhead Well he's asking for details about his specific flight and whether we could get them. Perhaps it's a bit more case by case than that question.

At the risk of stating the obvious: (1) planes are big, and (2) 1000 feet is a shorter distance than you might think. (It's about 300 meters, or 0.2 miles or the height of the Eiffel Tower or six olympic swimming pools for US readers. ;)) A plane flying past yours at a distance of 1000 feet looks very close, especially in the middle of the sky with nothing else around to compare the distance to.

@IlmariKaronen how many banana is that?

@vasin1987 around 1700-1900 banana depending on their size

It varies but I'm pretty sure nothing wrong has happened during your flight.
Vertical Separation: RVSM (Reduced Vertical Separation Minimum) reduces the standard vertical separation between aircraft from 2,000 feet to 1,000 feet for flights between flight levels 290 and 410 which is 29,000ft to 41,000 (at sea level, flight levels do not account for elevation of the area).
I've checked the FlightRadar24 logs from yesterday of EasyJet Flight 2142 (U22142/EZY98NU).
The closest Condor flight to your EasyJet plane was Condor Flight 1654 (DE1654/CFG7HT) from Leipzig to Kos Island. It was at ~35,000ft when it came near your plane and you were at 36,000ft. It was D-ANMY, a green-stripe livery A321, just as you described.
Image of this plane:

(Source)
It happened around Budapest, Hungary. This is RVSM airspace. The required vertical separation is 1000ft, which was maintained properly here. The planes just almost passed over each other if you are interested in that.
Flightradar24 link for your flight - here and for the Condor flight - here.
They came like this

Before passing like this

If there was anything wrong with the jets that caused them to be too close by the standards, there's TCAS (Traffic collision avoidance system) on all airliners that would alert the pilots very accurately and tell them to climb or descend accordingly.

How did you get all that info? I mean what flight, an image of the Condor flight, the flight number of the Condor flight, the location at which it happened, the departure and destination of the Condor flight, specifics of the aircraft, ...etc all that and in less than an hour? I'm just curious. Great answer, BTW.

@AircraftEnthusiast007 I used Flightradar24 to go to the departure time of that flight in playback. Then I put a filter just for Condor planes, and selected the EasyJet plane. Then with the API I checked the coordinates of the closest planes, this came up, and I used the website to show how it happened. Takes 15 minutes.

Wow, that's superb. So Flightradar24 is open to public?

@AircraftEnthusiast007 yes most features of FR24 are free, there is also a subscription with more functionalities. Another service like that is globe.adsbexchange.com

Thankyou so much for taking the time to look into you have answered it fantastically well and it’s much appreciated

@EddieM if you think this is correct answer you can mark it as correct.

@EddieM Please see this article in the [help]: What should I do when someone answers my question?

thanks for this amazing level of detail, wonderful!

I created an account just to vote this up. Great answer.

@Dave, well I hit the 200 cap today, so your upvote won't give me rep... it doesn't roll over to the next day... thanks anyway!

gold medal answer !


text:
Converting FAA CPL to EASA
Hello I currently live in the USA. I hold a CPL with an IR and I am currently in Multi Engine and getting ready for my check ride. I would like to move to Europe and work for airlines there. However I am finding it quite difficult to find anything that helps me or lays out this process. If anyone has any information that can help that would be great. Some of my main questions are:

How long would this process take?
Do I have to redo any of my check rides to convert them?
Is there anywhere here in the USA that with the conversion?
Is there anyone out there that has done this process?

Any answers help. Thanks.


text:
Why helicopters don't use complete tail rotor guard?
Knowing that there is a difference between a tail rotor guard and Fenestron (which also serve as a guard and is present in many helicopter designs), I came across this UltraSport Helicopter and wondered why more helicopters don't use a complete tail rotor guard like it?

Source
Instead the ones that have some guard only use a half guard like the Enstrom280FX or R44?

Source1 Source2

For a small (tiny) helicopter as linked in the first pic, it is entirely possible for a person to be able to interact with the top of the tail rotor. Obviously, if this was spinning, bad things will happen.
On any larger helicopter, the top of the tail rotor arc is out of reach of an adult human. Only the bottom needs to be protected from a tail strike.
It started out as a ducted fan. Control anomalies caused them to ditch the duct. But retained the full ring for protection.
Going to the original manufacturers info:

The tail rotor ducted fan shroud has been replaced with a flat shroud because of an anomaly observed during flight testing which resulted in a reversal of stick position as a function of forward speed.
A more conventional tail rotor has been substituted, though the vertical fin has retained the ring configuration to serve as both a stabilizer as well as a protection system for the tail rotor – something it does very well. The tail boom is a metal construct and the later versions of this assembly have been mounted higher in relation to the fuselage in order to add some ground clearance.

https://www.redbackaviation.com/american-sportscopter-ultrasport-496-helicopter-ultrasport-254-helicopter/
Fun off topic fact: Both the now defunct original manufacturer, American Sportscopter, and the follow on company, Advanced Technologies, Inc.....exist in the business park about 1 mile from my house.

ok makes sense. What about the case of a helicopter taking off on a tight space near electric wires or trees?

@Gabe - For that, you'd also have to worry about the main rotor. Which you can't 'protect'.

You are correct, I didn't realized how long a typical main rotor is, looking at it closely, it almost overlaps the tail rotor.

I think the guard is only there for tail strike protection rather than to prevent people from walking into it. If it's for protecting people, why is there no guard on the rotor side?

The guard that's alternately red and white is so as a warning, not just as decoration.

In short
Let's not mix a rotor guard, a protection against tail strikes, and a ducted fan (one trademark is Fenestron), a different family of propellers. The former belongs to landing safety, the latter belongs to aerodynamic efficiency.
Contrary to the duct of a ducted fan, the rotor guard is regulated, it must prevent the tail rotor to strike the ground when landing, hence the protection is located at the bottom of the rotor, but it often extends forward and aft to prevent contact with walls and obstacles during ground handling.

Rotor guard

Why helicopters don't use complete tail rotor guard?

This guard is not designed to prevent someone to be in contact with the blades. This would require some kind of cage like for boat propellers. Rotors, like propellers on aircraft, have no such requirements.
The role of the tail rotor guard (TRG) is to prevent the blades from striking the ground while maneuvering close to it or when landed. From this Pilot Training Guide:

Tail Rotor Guard: A tubular aluminum tail rotor guard is installed on the aft end of the tailcone. It aids in ground handling and protecting the tail rotor from damage while the helicopter is on the ground.

An example of TRG which cannot protect people, but is enough to prevent a tail rotor strike (Hughes 300C):

Source: Martijn Koetsier at PlaneSpotters.net
Many TRG looks like a half oval protecting the bottom part of the rotor against contact with the ground, but also the rear and bottom parts from contact with the walls and other obstacles to facilitate ground handling.
The TRG design is regulated in relation with the landing:

§ 29.411 Ground clearance: tail rotor guard.

(a) It must be impossible for the tail rotor to contact the landing surface during a normal landing.

(b) If a tail rotor guard is required to show compliance with paragraph (a) of this section—

(1) Suitable design loads must be established for the guard: and

(2) The guard and its supporting structure must be designed to withstand those loads.

Ducted fan

I came across this UltraSport Helicopter and wondered why more helicopters don't use a complete tail rotor guard like it.

The complete ducting seen on some anti-torque rotors is more comparable with an aircraft ducted fan, a different propeller family. This design is found on some rotorcraft, but also on aircraft, on hovercraft and on airships. On helicopters it is known, according to Wikipedia as a "fantail or by the trademark name Fenestron". E.g. on a Eurocopter EC120:

Source.
Note there is a Fenestron, but also the regulated TRG at its bottom.

As referenced in my post's first link, I was aware that the guard was designed to protect the tail rotor, not the person. However, it can't be denied that it can help provide some protection for a person just like a fenestron can also help.

"Rotors are not better protected than propellers." what do you mean by that?

@Gabe Compare helicopter tail rotors to prop driven aircraft propellers. Nothing stops a person from walking into a spinning propeller.

As a point of clarification, do you mean "Not designed for the safety of persons outside the aircraft"?  I would think the one of the purposes of the guard is to prevent harm to occupants of the aircraft that could otherwise occur if the counterbalancing torque supplied by the tail rotor were to suddenly go away while the craft was near the ground.

@mins: In the absence of a guard, could a tail-rotor strike not cause the tail rotor to quickly fly apart and render the aircraft uncontrollable so as to risk harm to the people inside?  Probably not fatal harm, given the altitudes involved, but harm nonetheless?

@mins: If a rotor strike could be potentially fatal to the occupants of an aircraft, any equipment to prevent that would protect the safety of aircraft occupants.  Your answer claims, however, "...this guard is not designed for the safety of persons."  The guard may not be designed for the safety of persons outside the aircraft, but I'm pretty sure that a lot of aircaraft occupants would want to be considered "persons".

As a layperson and non native speaker of English reading that, I can tell that "not designed for the safety of persons" is easily understood as "not designed to prevent people from colliding with a spinning rotor" as intended. Stating that any part of an aircraft is designed with the safety of people (inside or outside the aircraft) in mind seems just stating the obvious.

unreal but it just happened recently: https://www.youtube.com/watch?v=4wMeTCxZoDk

From the website you linked under "UltraSport Helicopter":
"The tail rotor ducted fan shroud has been replaced with a flat shroud because of an anomaly observed during flight testing which resulted in a reversal of stick position as a function of forward speed."
So this a ducted shroud that had its duct removed, rather than a top-and-bottom-guard.

This is an excellent example of how the development of aircraft can produce unexpected end results even from tried and true solutions.

People walking near an idling helicopter will often duck under the tail boom instead of walking around it. People practically never attempt to climb over the tail boom instead.
Helicopter designers typically take advantage of this behavioral trait to save weight by omitting the unused upper half of the rotor guard.
I can't tell what that thing on the tail of the American Ultrasport is supposed to be. Apparently they couldn't make a duct fly but are reluctant to give it up, so they mounted a sort of a picture of a duct.


text:
What is the effect of fuselage weight on a model glider?
I've built a model glider and wanted to see the effect the weight of the fuselage had on its performance. It flew the further with more weight which seems counter intuitive. I can exert more force into the glider with more weight which results in greater airspeed, would this be the reason for the increased glide ratio? How does this compare to real life gliders? Thanks.

See here for the answer: Why would a glider have water ballast? If it is trying to stay aloft without an engine, wouldn't it be better to be as light as possible?

Variations in aircraft weight do not affect the glide angle provided that the correct airspeed is flown. Since it is the lift over drag (L/D) ratio that determines the gliding range, weight will not affect it.
The glide ratio is based only on the relationship of the aerodynamic forces acting on the aircraft. The only effect weight has is to vary the time the aircraft will glide for. The heavier the aircraft is, the higher the airspeed must be to obtain the same glide ratio.
If two aircraft have the same L/D ratio but different weights and start a glide from the same altitude, the heavier aircraft gliding at a higher airspeed will arrive at the same touchdown point in a shorter time. Both aircraft will cover the same distance but the lighter one will take a longer time to do so.

Even if your ballast doesn't change the CG location, there's a "sweet spot" airspeed at which the wing is most efficient (L/D ratio is highest), and this is always faster than minimum sink speed.  It's usually possible to trim a glider to fly at best L/D without ballast, but this requires nosing down, which increases sink more than adding correctly located ballast.

Real-life gliders require some minimum payload to have their C.G. within limits; without this they can't hit their performance numbers. For this reason it is common to ballast a 2-seat glider with a sandbag if it is operated by a single occupant: the glider pilots say that if underweight, the glider "penetrates" poorly i.e., it cannot be trimmed into a minimum sink rate state that also is comfortably above the stall. When underweight, the glider mushes along at low airspeed in a poorly-controllable state.
In my experience with model gliders, they too will fly poorly without ballast: hand-launching an underweight glider causes it to pitch up, then quickly lose airspeed and descend more like a parachute than like a glider.

Thanks, if we had two identical life size gliders but one was heavier then the other, which would go further?

The pitch up is caused by a too backward cg. location and the parachute-like descent means that it is fully stalled. You fly it with the wrong cg location!

yes, my point was that the hand glider, straight out of the box, required ballast to get the CG correct.


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How much air does a GE90 ingest at sea level and at cruise level per meter?
I just wanted to know how much air PER METER a GE90 turbofan engine sucks in considering the same thrust output at different altitudes to better understand how the engine can travel further while burning the same amount of fuel at cruise level.
As we all know, air gets thinner as we go higher. The engine operates at a certain air-fuel ratio, and that means that at ground level where air is thicker the engine needs to travel less metres to ingest enough air to combust a unit of fuel then when it is at, say, 35.000 feet.
I found elsewhere that the GE90 operates at an air-fuel ratio of 33,3:1 meaning that it needs 33,3kgs of air to combust 1kg of fuel.
What I'd like to know is how many metres it has to travel to ingest said mass of air at ground (sea)level with a density of 1,2985 kg/m3 at 19C° and at 11.000 metres with a density of 0,3639 kg/m3 at -56,5C° (values taken from the table at this page)
Can anybody provide any help?

This has to be something to do with a university assignment.  That data is so specialized you need to contact someone at GE tech support or their engineering organization that can help you out.

The reason it can travel further with the same amount of fuel has to do with the drag of the aircraft being lower, it can go faster with the same thrust.

It doesn't have to travel any distance to suck in air, otherwise you'd never be able to start a jet engine until you were moving. There are engines that need a certain volume of air moving into them before they will start (ramjets/scramjets).

I'm voting to close this question as off-topic because the premise of the engine needing to travel a certain distance to be able to consume air for combustion is incorrect, therefore any answer would have to rewrite the question entirely.

The question is about the operation of an aircraft engine. It doesn't turn into another topic just because OP's assumptions are incorrect. It does make it unclear what is being asked, and that needs clarification. If he asked about mass flow instead of meters it might work.

From this answer a GE90:

has a mass flow rate of 1,350 kg/s at take-off and 576 kg/s at cruise (at 10.668 km = FL350).

It doesn't need to move at all to have air flowing through it. At stand still, the rotating compressor blades will suck air in. The air pressure will decrease as it accelerates towards the engine, then as the compressor increases its pressure as it flows through the compressor. So, its pressure will rise, and increase significantly higher than the ambient air pressure.
When the engine is moving, the air isn't sucked in, rather, it is "force fed", or "rammed" into the engine (speaking generally). This means it usually actually slows down as it enters the engine, and so it's pressure rises in the intake even before it's encountered the fan blades. (Thus known as a ram pressure rise).
Thus, the question "how much air per meter does a GE90 consume" is not a valid question because the amount of air does not depend on the forward speed of the engine, it depends very largely on the rotational speed of the compressor (determined by the throttle position), and to a much lesser effect, the speed of the aircraft (also determined by throttle and other aspects such as its weight, if it's climbing or not).
Basically, an engine takes the mass flow it wants, not what it's provided by the forward speed of the aircraft. If it's not moving forward, it's provided with nothing, so it sucks in the air it wants. If the aircraft is moving forward, such as in cruise, the intake area mutiplied by the forward speed is likely providing more air than the engine needs, so the excess air is spilt out of the intake.


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Are radio channels used by airliners half-duplex channels?
Can a pilot transmit and receive information at the same time? Or can he either transmit or receive but not at the same time?
I thought communication channels were half-duplex because this reduced the chance of the information by trasmitter (say the ATC) being overlapped by information from the receiver (the pilot) in case he possibily accidentaly pressed the PTT button. Is that a right assumption or not?

They are half-duplex because all parties share the same frequency. Only one party can transmit at any time. Full duplex would require two frequencies. Can you edit your question to clarify if you don't understand this aspect of communication.

That is very clear, thanks. So the reason behind the channels being half-duplex lies in the fact that it would be necessary the use of two frequencies for the two parties to transmit and receive at same time. But was it the intention of non being able to transmit and receive at the same time wanted from the start because (as I said) that would potentially create confused situations? Or is that just a plain technical limitation as having two frequencies assigned per aircraft is just non convenient?

Full duplex would require two frequencies and therefore third parties would have to monitor both frequencies simultaneously in order to hear both sides of the conversation. Half-duplex operation on a single frequency is inherently 'open-channel' - everybody can hear everything transmitted by anybody else on that frequency. That's the way it's always been done in aviation and in many other fields.

Full duplex isn't unheard of though in aviation, there are some frequencies that are transmit only or receive only (like listening for an FSS over a VOR and transmitting on a separate frequency).

@Fiddlesticks You should go ahead and make your comment an answer. They're trying to cut down on "answers in comments."

They are half-duplex because all parties share the same frequency. Only one party can transmit at any time.
Full duplex would require two frequencies and therefore third parties would have to monitor both frequencies simultaneously in order to hear both sides of the conversation. Half-duplex operation on a single frequency is inherently 'open-channel' - everybody can hear everything transmitted by anybody else on that frequency. That's the way it's always been done in aviation and in many other fields.
(Answer taken from comments by https://aviation.stackexchange.com/users/13124/transistor and https://aviation.stackexchange.com/users/15152/fiddlesticks)


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Are there regulations for water skiing in a ASEL aircraft?
What are the regulations regarding water skiing with ASEL aircraft, as in touching your tires down in a particular body of water such as a lake or river? Sometimes referred to hydroplaning.

Do you mean a) skimming the surface of the water with the aircraft's tires, or b) towing a water skier behind the aircraft?

Choosing between the two sounds like settling.

@Pondlife I can’t quite see how you would initiate b) - catch bungee type rope? exit flying aircraft with water skis attached? It would at least be conceivable with a float plane, but on a land plane... interesting!

Water skiing, water skimming and hydroplaning are all terms used to describe the intended activity.

@CptReynolds I don't know either, but I would bet a lot of fake internet money that someone somewhere has found a way!

@Pondlife Indeed! The trick is to transfer from a 60mph speedboat to a 80mph C152: https://youtu.be/XF7SnJCaanU

@CptReynolds look up the bucket drop maneuver. Bet you could use it to slowly transfer speed to a waterskier.

No regs against it but is strongly discouraged. If an accident did occur, you’re likely to be cited under 14 CFR 91.13 Careless and Reckless Operation and the incident will probably be used as evidence in a Wrongful Injury/Death lawsuit.

No "hydroplaning" with tires or "skimming" with skis is not illegal.
It's very common in Alaska and was supposedly started (~1930-1935) by bush pilot "Bob Reeves" delivering freight with skis from Valdez Alaska mud flats to higher snow covered altitudes and glaciers. It's now common among J3 Cubs with balloon tires (often Goodyear Blimp tires).

Youtube clip of Bob Reeves landing on mud flats in 1938.
While most of use know the rating as a "Float Rating", the FAA officially designates the privilege as a "Seaplane Rating". Therefore the aircraft must be in a "seaplane" configuration in-order to require a special license.
Amazingly, the FAA does not require a sign-off or special training for skis - despite the fact there can be as much or more of a difference in technique compared to the mandatory tail wheel sign-off!

The original useful purpose for skimming was to allow landing by bush planes in tight areas near water. This is what is meant by skimming:

Youtube
and there are no specific regulations against doing it.

Like a lot of things where there are no legal prohibitions, the real issue is if you have in-motion hull insurance or not.  If you don't have in-motion hull, knock yourself out.  If you do, better make sure its covered, otherwise you'll be in for a surprise if you mess up.

Most insurance companies I have dealt with won't even cover insurance for an accident on a dirt strip; it has to be an "improved" runway i.e. paved and lighted.